Generally, a cellular network topology is applied in a modern wireless communication network. There are many other adjacent cells around a cell covered by a base station, while only one or more cells generally are applicable to serve as a target cell for handover or redirection of a User Equipment (UE). In addition, handover or redirection is controlled by the base station of the network side, which requires the base station to make a right choice among these adjacent cells. Generally, when handover or redirection is performed, the UE needs to firstly report signal qualities of adjacent cells to the base station, and the base station then selects an appropriate target cell according to a reporting result of the UE, a network load and other information so that handover or redirection is performed by the UE. In this way, an optimal cell is selected through handover or redirection, thus ensuring the success rate of handover or redirection.
However, when handover or redirection is performed, a wireless link is established between the UE and the base station. In other words, both a receiver and a transmitter of the UE are working. Due to the influence of cost, complexity, portability and other factors, the UE is generally provided with a set of receiver and transmitter, thus the UE has difficulty in measuring the signal qualities of other adjacent cells and can hardly use the working receiver to measure other cells. During data reception and transmission, it is even more difficult for the UE to change a working frequency or system to measure other adjacent cells especially those with different frequencies and systems.
In order to enable the UE to measure other cells during data reception and transmission, it is agreed with the UE in advance in some standards that the UE will measure other cells without receiving and transmitting data within a certain period of time. For example, a measurement interval mechanism is specified in a Long Term Evolution (LTE) standard, and the measurement interval mechanism includes: a measurement interval of 8 ms is allocated to the UE every 40 ms. Both the UE and the base station do not receive and transmit data within the measurement interval so that the UE can measure an adjacent cell. However, this is at the cost of sacrificing data transmission performance. For example, a decrease of 20% in data throughput may be caused at most according to the LTE standard.
It is also time-consuming if the UE needs to measure signals of an adjacent cell within a certain period of time and report the signals of the adjacent cell to the base station and the base station then selects a target cell according to a measurement result. Usage experience of a user may be also affected due to non-timely handover or redirection, especially when the UE needs to perform handover or redirection immediately on occasions including a high speed motion and the like.
Due to the influence of the factors above, not only optimized handover or redirection with measurement is applied, but also blind handover or redirection is widely applied in modern wireless communication networks at present. Blind handover or redirection refers to that a base station directly orders a UE to switch or redirect to a certain target cell without requiring the UE to measure an adjacent cell and to report a measurement result. However, an inappropriate target cell may be selected by blind handover or redirection of the base station after all without a measuring result as a selection basis, which results in a failure and influences user experience. If unsuccessful handover or redirection is repeated for many times, network resources may be further consumed.